1. Field Of The Invention
The present device relates to an optical disk player, particularly to an optical disk player having a tilt servo mechanism by which the recording surface of an optical information recording disk and the optical axis of light irradiated upon the recording surface are kept perpendicular to each other.
2. Background Art
FIG. 8 shows a major part of a conventional optical disk player in which a disk 1 is on a turntable 3 which is rotated by a spindle motor 2. The disk 1 is pushed on the turntable 3 by a clamp mechanism including a clamper 4. The disk 1 may be deformed as a dish with its concave side facing down. The spindle motor 2 is secured to a fixed base 5. A movable base 6 is attached to the fixed base 5 by a support pin 7 so that the movable base can swing in a direction P. A guide shaft 8 is provided on the movable base 6 and supports a carriage 9 so that the carriage 9 is slidable on the guide shaft 8. An optical pickup is housed in the carriage 9. The optical pickup comprises an optical system including an objective lens 10 and a lens servomechanism for performing the servo driving of the objective lens 10 in a direction of focusing and in a direction of tracking. The optical pickup functions so that laser light is irradiated upon the recording surface of the disk 1, the laser light is reflected by the recording surface and received by the optical pickup, and the change in the reflected laser light is detected to read recorded information. A carriage drive (not shown in FIG. 8) moves the carriage 9 along the guide shaft 9 and a base rotator (not shown in FIG. 8) applies a swinging force to the movable base 6 to rotate it relative to the fixed base 5. Both the driver and the rotator are provided in the optical disk player. A detector (not shown in FIG. 8) comprising a light emission element and a light reception element, for example, is provided on the carriage 9 to detect the angle of relative tilt between the optical axis of the laser light and the recording surface of the disk 1 and to generate a detection signal. When the carriage 9 is moved outward in the radial direction of the disk 1 along its recording surface, the detection signal is sent from the detector to a control circuit so that the control circuit acts to appropriately operate the base rotator depending on the detection signal to keep the optical axis of the irradiated laser light and the recording surface of the disk perpendicular to each other.
When a dropout occurs in the optical disk player due to a flaw in the recording surface of the disk 1 or the like so that a reproduced signal is not generated, a tilt servo means is likely to perform an improper tilting operation so that the movable base 6 is excessively swung and the pickup including the carriage 9 abnormally approaches the disk.
If the conventional optical disk player is of such a type that the tilt servo operation is not performed when the carriage 9 is moved toward the radially innermost portion of the recording region of the disk 1 after the end of reproduction, the carriage 9 which is greatly tilted to correspond to the greatly tilted radially outer part of the disk 1 as shown in FIG. 8 is moved inward in the radial direction of the disk 1 along its recording surface so that the pickup likewise abnormally approaches the disk.
For these reasons, the conventional optical disk player is provided with an abnormal approach prevention mechanism for detecting the above-mentioned abnormal approach beforehand and it thus prevents the misoperation. However, since the abnormal approach prevention mechanism includes expensive components such as a detection switch and the number of the component parts of the mechanism is large, the cost of the mechanism is high.